In magnetic resonance imaging, Gadolinium-based contrast agents are often infused into a subject body in order to increase signal sensitivities. However, in some cases, contrast agents are detrimental. For example, contrast agents used in renal imaging become a risk factor for Nephrogenic Systemic Fibrosis (NSF). As for cephalic imaging, Gadolinium deposits remain in the brain after imaging, which becomes a health concern. Thus, non-contrast imaging methods are preferable.
In this context, Time-SLIP (Time-Spatial Labeling Inversion Pulse) is a non-contrast MRA (Magnetic Resonance Angiography) technique using ASL (Arterial Spin Labeling) that provides a user an angiogram whose image quality is equal to or even superior to contrast-enhanced technique. In Time-SLIP method, an inversion pulse is applied and data acquisition is performed at a subsequent imaging sequence during a time period near the null point in which longitudinal magnetization of background tissues becomes substantially zero. Hence, background signals become obliterated and signals of interest become conspicuous.
In data acquisition, Cartesian acquisition is usually used in Time-SLIP method. However, Cartesian acquisition employed in the imaging sequence of a Time-SLIP pulse sequence precludes a magnetic resonance imaging apparatus from robust sampling against motion artifact.